The present disclosure relates to treatment systems, specifically to a low-energy treatment system for low-flow acid and alkaline drainage located in remote areas.
The precipitation of heavy metals from acidic or alkaline metal-laden water requires large amounts of dissolved oxygen to complete chemical reactions at certain pH plateaus. Complete oxidation of the heavy metal precipitant is key to producing a stable metal precipitant, thereby producing a stable filtered or decanted water for discharge after treatment. Reduced environments (dissolved oxygen deficient) remain unstable and the final pH and or residual metal content of the discharge water is unpredictable.
Air compressors and paddle type agitators used in prior art heavy metal treatment systems consume large amounts of energy during the oxidation and agitation phases of heavy metal precipitation. The efficiency of compressed air bubblers, used in aerating metal laden waters, depend on bubble size and the distribution of these bubbles in the water during the treatment phases. Agitation of the heavy metal laden waters with paddle type or propeller type blades require large amounts of energy, as they operate within tanks and move large amounts of water, in order to assure adequate introduction and mixing of oxygen enriched waters and pH adjusting reagents during treatment of heavy metal laden waters.
The prior art treatment systems rely on air compressors to add atmosphere to the heavy metal laden waters in order to raise the dissolved oxygen content of the water during treatment phases. Efficiency of the compressed air and the absorption of oxygen by the heavy metal laden water during treatment, depends on bubble size and the distribution of these bubbles within the prior art deep tanks. Excess amounts of compressed atmosphere must be added to insure that adequate oxygen is absorbed by the heavy metal laden water during the treatment and formation of the precipitants. This requires large amounts of energy to be expended in order to insure adequate oxidation takes place. Additionally, the remote nature of many impacted sites that require treatment systems often lack commercial electrical power.
Paddle type agitators used in prior art treatment systems move slowly within deep tanks and are largely unable to liberate the coated and un-reacted alkalinity providing reagent, thereby requiring the additional addition of reagent, to compensate for the un-reacted reagent previously added. The efficiency of the ionic exchange is also compromised as the large sized particle is not as efficient as a small particle during the formation of the precipitant. Prior art paddle type agitators also require and consume large amounts of energy as they have to move large amounts of water within deep tanks.
What is needed in the art is a treatment system designed to improve the efficiency of the oxidation and agitation phases of heavy metal precipitation during treatment, while utilizing a low-energy consumption power source.